The phrase "a first indicator" is correct and usable in written English.
It can be used when referring to an initial sign or signal that suggests a particular condition or outcome.
Example: "The increase in temperature is a first indicator of the impending storm."
Alternatives: "an initial sign" or "a primary signal".
A first indicator against which to make that judgment is the ratio of gross public debt to GDP.
Thus, a low sum score is a first indicator of a low quality of the solution.
A first indicator map on a 1 km grid for the EU is provided, based on available data.
This is a first indicator that anticommunism in the Federal Republic underwent a change from the early 1960s onwards.
The target level of methane productivity or better methane yield can be used as a first indicator of M&C requirements.
Even though its use as instrument is not indisputable it serves well as a first indicator for how intermarriage relates to specialization.
Both experiments included the indicator stimulus condition used previously for aimed-movement responses in which one of a set of outline circles, each marking a possible response, filled in to indicate the required response and pitted it against a second indicator stimulus that differed across the experiments.
Water quality is soon to become a sixth indicator, with biodiversity due to become a seventh later in the year.
A fifth indicator showing the percentage of pupils who continue in education, employment or training during the year after they finished their key stage 4 qualifications, may be introduced at a later date.
In the government's response to the Francis inquiry, Hunt announced an investigation under the NHS medical director, Sir Bruce Keogh, of 14 hospital trusts in England that also had high mortality rates under HSMR or a second indicator, SHMI.
A third indicator will be a change in the direction of the magnetic field lines.
